Project Title:

Aspheric Surface Figuring Using Plasma Assisted Chemical Etching

08.20-1667
900688
Aspheric Surface Figuring Using Plasma Assisted Chemical Etching

Abstract:

The proposed project is designed ultimately to result in an automated method for
the direct fabrication of finished, precision aspheric surfaces on silicon optical
elements using a plasma assisted chemical etching (PACE) process. This method would
make possible the figuring of such surfaces, beginning with simple polished, spherical
substrates in a single operation. The Phase I effort will focus on the selection
of appropriate plasma parameters and fluorinated etchant gas chemistries which produce
sufficiently smooth surface etching, while providing the removal rate and etch footprint
character necessary to produce smooth figure using our automated aspherizing approach.
Experiments will be conducted using silicon wafers to quantify removal rates, footprint
contours and surface roughness using candidate PACE configurations.j  These experiments
will employ our existing prototype PACE aspheric figuring system. The results of
the Phase I Program will define a plasma etching configuration which can meet the
requirements of the automated one-step optical figuring process.
The resulting capability would make possible the use of inexpensive aspheric silicon
optical elements in systems which operate in the 3-5 micrometer infrared wavelength
region. The anticipated simplification and improved performance of these systems
would make possible significant cost reduction.
plasma, etching, aspheric, figuring, automation, optics, silicon, infrared